Sydney: The Australian Transport Safety Bureau has ordered Qantas to conduct detailed checks on its Rolls-Royce-made Airbus A380 engines after it identified a potential manufacturing defect which it said could lead to an oil fire and engine failure.

The new checks come just days after Qantas resumed flying its A380s following a three-week grounding pending engine changes and checks as it investigated a 4 Nov engine failure on a jet with 466 people on board.

“The problem relates to the potential for misaligned oil pipe counter-boring, which could lead to fatigue cracking, oil leakage and potential engine failure from an oil fire," the ATSB said in a statement.

Qantas said it would begin the checks immediately but did not expect them to take more than a few hours and unless problems were detected, aircraft would not be removed from their rotation.

Qantas has already replaced four engines on its fleet of six A380s and continued to examine another 12 engines which may need to be replaced or modified, a spokesman said.

Qantas has not given a prediction on the cost of the outage but UBS estimated it may cost the airline around A$60 million ($58 million) in costs and lost revenue.

However, it remained uncertain when Qantas would fully resolve its A380 difficulties.

Only two of its six superjumbos are back in service and the rest of the fleet will be grounded into next year as engine checks progress. The airline will receive two new A380s later this month and analysts said that may ease some of the airline’s capacity constraints.

However, Qantas will continue keep the A380 off its routes to Los Angeles, among its most lucrative routes, as these flights require maximum engine thrust on take-off and the airline seeks time for investigations to conclude.